Copper iodide rectifier



Dec. 13, 1932. w, ss 1,891,097

COPPER IODIDE RECTIFIER Filed Sept. 8. 1950 Fig. I

Inventor: Walther- Krauss,

His Attorneg.

Patented Dec. 13, 1932 UNITED STATES PATENT orrlce WALTHER KRAUSS, OFBERLIN-ZEHLENDORF, GEBMANYpASSIGNOR '10 GENERAL ELECTRIC COMPANY, A.CORBOBATION OF NEW YORK COPPER 10mm. RECTIFIER Application filedSeptember 8, 1930, Serial No. 480,404, and in Germany October 3, 1929.

My invention relates to alternating current rectifiers of the solidelectrode or dry plate type, particularly to rectifiers of'this typecomprising copper iodide elements, and

its ob ect is the provision of an improved copper iodide rectifier andof animprovecl method of'preparing the elements therefor.

In the use'of dry rectifiers in which the discs are built up of copperiodide in contact with electrodes of various materials, it has beenobserved that the rectifying eifect weakens after a comparatively shortperiod of operation. It is believed that this disadvantageous action ofthe copper iodide rectifiers previously known is due to a polarizationeffect, since experiments in which the rectifiers were subjected to theaction of direct current before being used for the rectification ofalternating current have shown that in the use of such rectifiers theratio of the alternating current supplied to the rectifier to the directcurrent output thereof is dependent on the direction, amount andduration of the direct current passed through the rectifier in thispreliminary treatment, and that such preliminary treatment with directcurrent exerts,

in general, an unfavorable influence on the ratio of input to output ofthe rectifier.

In accordance with my invention, the injurious action of the above-notedpolarization efieot is substantially eliminated by the addition tothecopper iodide of oxidizing means, preferably iodine. I have found thatby the addition of a suitable amount of iodine to the copper iodide, theratio of alternating current input to the direct current output of thecopper iodide rectifier becomes substantially independent of thepreliminary treatment with direct current,- and at the same time 4()much longer operating life of the rectifier is attained. If curves weredrawn which rep resented the ratio of alternating current input .todirect current .output independence on the preliminary treatment withdirect ourrent, for example, to a given duration of the time ofpreliminary treatment t, they would show an average slope,

(a. 0. input) (d. 0. output) from the following description-whenconsidered in connection with the accompanying drawing and its scopewill be pointed out in the appended claims. v

Referring to the drawing, Figs. '1 and 2 are respectively a plan viewand cross-section of a rectifier disc embodying my invention.

In the figures a single rectifier disc 1 i5 shown comprising acomparatively massive plate of copper iodide 2 between a lead plate 3and a layer of copper 4. The plate 3 may be-of thin lead foil on whichhas been formed a layer of lead sulphate 5; the layer 4-pref- 7 erablyconsists of finely' powdered copper. In forming the complete disc 1,lead plate '3 is placed at the bottom of a die in a press and iodidemixture is poured-on the lead. After the iodide has been pressed lightlyto 0 produce a smooth surface the copper powder is distributed uniformlyover the surface. The layers are then pressed together strongly and ahard, dense disc is thus obtained. As hereinbefore explained, inaccordance with the present invention means are provided to avoid thepolarization difficulties heretofore encountered in the use of copperiodide rectifiers. To this end, the material forming the layer 2 is notcopper iodide alone but consists of pure co per iodide to which has beenadded a suitab e oxidizing a ent, preferably free iodine, to the extent,0.3%. The lead sulphate 5 on the su plate 3 facilitates the formation ofa thin coating of lead iodide 6 on the lead plate by the action of thefree iodine in the copper iodide after the operation of pressing of thedisc, iodide is the seat of the rectification of alternating currentwhen the disc is incorporated in a rectifier circuit. a

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A rectifier comprisin a lead electrode having a lead sulphate sur aceformed thereon, and an element in contact with said surface comprising amixture of copper iodide and free iodine.

2. The combination in a rectifier of a lead electrode, a layer of leadsulphate on the surface of said electrode, an element comprising copperiodide and free iodine mixed therewith, and a coating of lead iodideformed b the action of said iodine on: said lead sulphate between saidlead electrode and said element. In witness whereof, I have hereunto setmy hand this 19th da of August, 1930.

I ALTHER KRAUSS.

or exam le of race of u and this thin coating of lead

